White balance lens cap

Discussion in 'Accessories' started by manateeman90, May 20, 2013.

  1. manateeman90

    manateeman90 TalkEmount Rookie

    10
    Nov 29, 2012
  2. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    I don't know about these. If I'm shooting on the field, I shoot RAW anyways and don't have to nail the white balance, and if I'm on a shooting I'll bring a color profiler (or at least a white balance card) with me anyways, so no reason for a semi-accurate tool there.

    I'd say the auto WB is good enough in most situations and I - personally - wouldn't buy these caps.
     
  3. xXx1

    xXx1 TalkEmount All-Pro

    Jan 15, 2013
    The idea with white balance caps is same as white/grey card. You take a photo with it and use that photo to determine white balance in next photos. I don't know if Nex has got a feature that uses the white balance cap to balance the photos but white card is free and probably more accurate.
     
  4. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    Yeah, a white card IS more accurate. Why? The lens cap gets backside illuminated (transmitted light) whereas a white card uses reflected light, which is the light you're using when capturing the photo. I actually don't know how big the difference is going to be, but I don't see the need for such a lens cap.
     
  5. davect01

    davect01 Super Moderator

    Aug 20, 2011
    Fountain Hills, AZ
    Dave
    They do seem like a nice idea as it eliminates another product being needed, but they are not as accurate as a card for the reasons listed.

    I recently found a neat feature in the White Balance Menu simply called "White Balance." You find something white, take an image, and it sets the White balance to this.
     
  6. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    Well, that is how you do it with white cards, you know? ;)
     
  7. xXx1

    xXx1 TalkEmount All-Pro

    Jan 15, 2013
    It can be very big. Think about inside a brick building or big grass field.
     
  8. manateeman90

    manateeman90 TalkEmount Rookie

    10
    Nov 29, 2012
    Aah, thanks for your collective insight :) what is the best way to make the most accurate white balance card?

    I've always wondered about the logistics behind a white balance card. When doing a custom white balance, does the card have to fill the whole screen with white? I was worried that if this can only be achieved with the card very close to the lens, it would make the picture very dark and I wasn't sure whether this would impact on the accuracy of the custom white balance?
     
  9. xXx1

    xXx1 TalkEmount All-Pro

    Jan 15, 2013
    Any white piece of cardboard is close enough to white. Grey card is even better as you can pinpoint exposure too. White/grey card doesn't need to be very big and it is enough that you can pick the color temperature off it with the raw developer you use.

    I think that grey lens cleaning cloth is one of those great little inventions, I am going to get one in autumn (I don't order anything from China now as my summer vacation is approaching).
     
  10. manateeman90

    manateeman90 TalkEmount Rookie

    10
    Nov 29, 2012
    What do you mean by "grey card is even better as you can pinpoint exposure" and "pick the color temperature off it with the raw developer you use"

    I use adobe lightroom to import my photos and I shoot in RAW
     
  11. xXx1

    xXx1 TalkEmount All-Pro

    Jan 15, 2013
    There is usually a pick tool to pick neutral color in raw development tools. You point mouse to some white or gray part of image and press mouse button and program measures how color temperature should be corrected. With gray card it is very easy to adjust exposure, you check that gray card image isn't too dark or too light. I know nothing about Lightroom, I use Raw Therapee.
     
  12. manateeman90

    manateeman90 TalkEmount Rookie

    10
    Nov 29, 2012
    Oo i get you, we are on the same page now :) ta
     
  13. loonsailor

    loonsailor TalkEmount Regular

    45
    Feb 7, 2013
    Berkeley, CA, USA
    I haven't used that specific device, but I've used other shoot-through diffusers and found that they don't work well. I used these Stephen Johnson Photography Digital GrayCap and they work great. Shoot raw, take a shot of the lens cap once in a while when the light changes, and balance with the eyedropper tool in lightroom. The only problem I've had is that they don't fit on many of the small lens caps for my Sony system, so I need to cut them in half. Still works fine, of course, just an extra step in mounting them.
     
  14. xXx1

    xXx1 TalkEmount All-Pro

    Jan 15, 2013
    Great idea. Now we need to convince a Chinese lens cap manufacturer to manufacture neutral grey lens caps. Preferably with color coding (inside) for cap size.
     
  15. dbmiller

    dbmiller TalkEmount Top Veteran

    779
    Mar 2, 2012
    New England
    My daughter and I share a 77mm Expo-disc. I just hold it in front of the lens for the shot, or use a step-up ring if I will also be using the big ND filter.

    There seem to be two theories on how to best use one:
    • Take the white balance shot from the same location from where you will be taking the picture. You get all the light reflected back at you that would be in the shot run through the disk/cap, and so the white balance would be the same as placing a white balanced card at the subject location and shooting it.
    • Stand where the subject is, and shoot towards the location from where you will be taking the actual shot. This will capture all the light coming in to the subject - Which means the white balance is more specific to the subject than the overall scene.
    You can contrive setups where one of the other might matter. But in most cases, they are are usually or nearly the same.
     
  16. loonsailor

    loonsailor TalkEmount Regular

    45
    Feb 7, 2013
    Berkeley, CA, USA
    The second method is correct. You care about the incident light on the subject, which is what gets reflected back to you. Of course, it's not always possible, and often the light is the same on you as on the subject anyway in which case it doesn't matter.

    Of course, you either need to use that reading to set a custom white balance in the camera. I've never tried that on the Sony, but I assume that it's possible. The other method, which I always use, is to shoot raw, not worry about the white balance in the camera, and correct in the post, using the eyedropper tool as described above. If you do that, it's vital that you shoot raw, because if you shoot jpg the camera will do it's own correction for each shot.